The invention discloses a key structure with a mechanical switch. The key structure comprises a keycap, a base plate, a lifting unit, an accommodation housing, an outer guiding cylinder, an inner rotating cylinder and an elastic assembly. The base plate is arranged below the keycap; the lifting unit is arranged between the keycap and the base plate to guide the keycap to go up or down along a pressing direction. The accommodation housing has a plurality of section plates arranged in an annular shape and a plurality of section recession zones formed between the plurality of section plates at intervals. The outer guiding cylinder is accommodated in the accommodation housing movably along the pressing direction of the keycap and is abutted against the bottom of the keycap. The outer guiding cylinder has a plurality of positioning protruding blocks protruding outwardly and a plurality of recession stopping parts. The inner rotating cylinder is accommodated into the outer guiding cylinder and includes a plurality of sliding protruding blocks. The elastic assembly is arranged at the bottom of the inner rotating cylinder and provides an elastic force facing the keycap for the inner rotating cylinder. In addition, the invention also provides a mechanical switch.